Uterine haemodynamics as a possible driving force for endovascular trophoblast migration in the placental bed

Uteroplacental vascular adaptation during pregnancy depends on retrograde e ndovascular migration of trophoblast in the uterine spiral arteries and the ir subsequent incorporation into the vessel wall. In the human, this migrat ion process occurs in a step-wise fashion, starting with plugging of the di stal ends of the arteries, followed by migration into the decidual and, aft er several weeks' delay, into the myometrial segments. The hypothesis is pu t forward that haemodynamical forces play an important regulatory role in t his process. A mechanical signal transduction system should then be present within the trophoblastic cells to trigger their rheotactic behaviour. Sinc e the condition of preeclampsia is characterized by restricted colonization of spiral arteries by trophoblast, the implications of this proposed regul atory system on the pathogenesis of the disease are considered. (C) 2000 Ha rcourt Publishers Ltd.